Every cup holder is slightly different and there are countless large mugs or bottles that don't fit in the standard cup holder. Having an adapter to fit your favorite water-bottle or mug is a must, and in order to be usable the model must be parametrically adjustable to fit your exact needs.

The basic Parameters are shown here:

Make sure to enable the following options if you want them:

• Angled top (for if your bottle/mug has tapered sides)
• Mug handle notch
• Inner ribs

The existing dimensions for the cup holder part will fit most cup holders I've tried it in, so you can see if those dimensions work as is or measure and modify to your liking.

Remember PLA will likely warp sitting in the your car in the sun - Print with PETG or better if you want it to last.